We propose to map the chromosomal integration sites of the DNA sequences of SV40, adenovirus 5 and Epstein Barr virus in virus transformed human cells using somatic cell hybridization techniques. The role of the SV40 A gene product in the proliferation of somatic cell hybrids between mouse peritoneal macrophages and SV40 transformed human cells will also be assessed. We will also produce somatic cell hybrids between totipotent mouse teratocarcinoma cells and SV40 transformed human cells to determine whether the integrated SV40 genome is not transcribed in the teratocarcinoma cells. In addition, we intend to continue our studies on the mapping of the chromosomal integration sites of Moloney and Kirsten sarcoma virus in virus transformed human cells. Somatic cell hybrids between HT-1080-6TG human fibrosarcoma cells and either mouse peritoneal macrophages or rat peritonea macrophages which segregate rodent chromosomes will be studied for the presence of Moloney, Kirsten and Harvey sarcoma specific DNA sequences to map the chromosomal location of these gene sequences in normal mouse and rat cells. In addition, we propose to map the structural genes of endogenous mouse RNA tumor viruses using HT-1080-6TG x mouse and Chinese hamster x mouse somatic cell hybrids.